Non-cleavable hinge enhances avidity and expansion of CAR-T cells for acute myeloid leukemia

Chimeric antigen receptor (CAR) T cell therapy is effective in lymphoid malignancies, but there has been limited data in myeloid cancers. Here, we start with a CD27-based CAR to target CD70 (“native”) in acute myeloid leukemia (AML), and we find modest efficacy in vivo, consistent with prior reports. We then use orthogonal approaches to increase binding on both the tumor and CAR-T cell sides of the immune synapse: a pharmacologic approach (azacitidine) to increase antigen density of CD70 in myeloid tumors, and an engineering approach to stabilize binding of the CAR to CD70. To accomplish the latter, we design a panel of hinge-modified regions to mitigate cleavage of the extracellular portion of CD27. Our CD8 hinge and transmembrane-modified CD70 CAR-T cells are less prone to cleavage, have enhanced binding avidity, and increased expansion, leading to more potent in vivo activity. This enhanced CD70-targeted CAR is a promising candidate for further clinical development. [Display omitted] •Azacitidine increases CD70 antigen density and potentiates CD70 CAR function•CD8H&TM-modified CAR-T cells have improved avidity and in vivo performance•In vitro avidity correlates with in vivo potency Leick et al. identify an immunotherapy strategy using CAR-T cells for leukemia by increasing binding avidity on both sides of the synapse through pharmacologic enhancement of tumor antigen density with azacitidine and via hinge modification on the T cell.